The present invention relates to a process for the Preparation of o-phthalaldehydes.
The o-phthalaldehydes which are the subject of this invention have the following formula: ##STR1## wherein R is selected from the group consisting of H, Cl, Br and CO.sub.2 H.
O-phthalaldehydes are well-known and long described in the literature. U.S. Pat. No. 4,206,152 describes a number of different processes for the preparation of these compounds. A process described in this patent comprises hydrolyzing at a pH of 4 to 11 an unsubstituted or substituted .alpha.,.alpha.,.alpha.',.alpha.', -tetrahalogeno-o-xylene with an alkali metal salt, alkaline earth metal salt or ammonium salt of a lower carboxylic acid or of an aromatic carboxylic acid in the presence of an optionally substituted tetra lower alkyl ammonium as phase transfer catalyst and of an alkali metal carbonate or alkaline earth metal carbonate at a temperature above 60.degree. C. When this process is carried out, it is found to take significantly longer periods of time than described in the patent to obtain the desired products and such is unsatisfactory from a commercial point of view.